A new genus of taeniodonts from the late Paleocene

UN" RSITY OF
ILLIi.jis LIBRARY

A,TURBANA-CHAMPAIGN
NATURAL HIST. SURVEY

FIELDIANA • GEOLOGY

Published by
CHICAGO NATURAL HISTORY MUSEUM

Volume 10 March 31, 1949 No. 6

A NEW GENUS OF TAENIODONTS
FROM THE LATE PALEOCENE

Bryan Patterson

Curator op Fossil Mammals

Until rather recently, knowledge of Late Paleocene members of
the peculiar mammalian order Taeniodonta was limited to frag-
mentary material from the Bear Creek local fauna of Montana.
Chicago Natural History Museum expeditions, working in the
DeBeque formation of western Colorado, Plateau Valley local fauna,
were fortunate in obtaining material sufficiently complete for ade-
quate comparison with previously known forms. Study of this
material indicates that the Late Paleocene representatives of the
group should be placed in a new genus, intermediate structurally,
and almost surely phyletically, between Psittacotherium of the Mid
Paleocene Torrejonian and Ectoganus of the Early Eocene Wa-
satchian.

I am publishing a review of the order in this series and a
discussion of its evolution elsewhere (Genetics, Paleontology and
Evolution, Princeton University Press). The review originally con-
tained the diagnosis given below. It now appears certain that the
discussion will be the first of the two to appear, thus making this
preliminary note necessary.

Order Taeniodonta

Family Stylinodontidae

Subfamily Stylinodontinae

Lampadophorus1 gen. nov.

Type species. — Lampadophorus expectatus sp. nov.
Referred species. — Psittacoiherium(1) lobdelli Simpson.
Distribution. — Late Paleocene. Plateau Valley local fauna, Colo-
rado; Bear Creek local fauna, Montana.

1 Xa/xwas, a5os, torch, and 4>opo%, bearer, in allusion to the light thrown by this
form on stylinodont taxonomy and phylogeny.

No. 623 41

42 FIELDIANA: GEOLOGY, VOLUME 10

Diagnosis. — Canines rootless, enamel-free portions more com-
pressed than in Psittacotherium. Cheek teeth with cement at bases
of crowns, roots with vestiges of former divisions; crowns higher
than in Psittacotherium, lower than in Ectoganus; little or no tendency
toward development of enamel-free bands on anterior and posterior
faces. Px~- smaller than in Ectoganus; ridges running externally
from protocones of PA A as in Ectoganus, more crenulated than in
Psittacotherium. M- wider than in Psittacotherium, hypocone less
isolated than in Ectoganus. P^_T with independent talonid crests.

Lampadophorus expectatus1 sp. nov.

Type.— C.N.H.M. No. P26083, incomplete skull and various
incomplete skeletal parts of an immature individual.

Horizon and locality. — Tiffanian; DeBeque formation, Plateau
Valley local fauna. Three and one-quarter miles west of DeBeque,
Mesa County, Colorado.

Hypodigm.— Type and C.N.H.M. Nos.: P15569, RP^; P15575,
LPT; P14906, RP*-T; P14954, P15008 and P26101, incomplete
lower molars (either MT or M¥); P26090, left humerus; P26093,
lower molar; P26106, lower canine; PM241, lower incisor. All from
Plateau Valley local fauna.

Diagnosis. — P- with crown more compressed antero-posteriorly,
main external cusp more centrally placed, postero-external cusp less
distinct than in L. lobdelli Simpson, incipient groove on internal face.

Lampadophorus lobdelli Simpson

Psittacotherium(l) lobdelli Simpson 1929, Amer. Mus. Nov., No. 345, p. 11.

Emended diagnosis. — PA longer antero-posteriorly than in L. ex-
pectatus, enamel prongs on external face better developed, postero-
external cusp more isolated, no groove on internal face.

JThe existence of a Late Paleocene genus intermediate between Psittaco-
therium and Ectoganus has been suspected for some time.